Aging is a virtually ubiquitous, progressive degenerative process. However nature has repeatedly produced species with both exceptional resistance, and exceptional susceptibility, to aging. We call these species of exceptional biogerontological interest (= EBl species), because of their potential to inform us both about the identity and nature of the destructive mechanisms that cause senescence as well as protective mechanisms of exceptional resistance to these mechanisms. The comparative biology of aging employs EBl species to address these issues. The overarching goal of the Comparative 8iology of Aging Core is to provide to researchers high quality, hard-to-get biological research materials from EBl species. Among mammals, we define EBl species as those living < 0.7 times as long as expected for their body size (the longevity of a mouse or less) or > 2.5 times as long as expected for its body size (the longevity of an average monkey or more). Additionally, because of their close evolutionary affinity with humans, we consider any primate regardless of longevity an EBl species. An important caveat is that we will only use species for which there is solid and unassailable documentation of longevity. The Specific Aims of the Comparative Biology of Aging Core are as follows: 1. Procure, crvopreserve. and provide to investigators cells and tissues from EBl species. A critical part of this aim is to ensure that cell culture growth conditions are optimized for each species. A second important component of this aim is to assure that biological materials come from healthy animals of known age. A final critical component to this aim is to communicate to the wider aging research community the availability of these biological materials to interested scientists. 2. Maintain research colonies, or purchase animals or tissues, of selected EBl species. This aim ensures that samples, even of fresh tissues, may be continuously available to the research community and takes advantage of the exceptional combination of extensive professional contacts in the comparative biology community and expertise in the husbandry of individual EBl species available at UTHSCSA. 3. Provide consultation and feasibility assessment for investigators wishing to pursue comparative aging studies. The Leader and Co-leaders of this core are uniquely positioned in terms of their expertise and contacts within the wider zoological research community to provide information, assessment, and guidance to interested investigators.